1. Field of the Disclosure
The disclosure relates to a display device, more particularly which can improve touch recognition capability in a gray zone where illumination of light created by a light source is similar to that of external light.
2. Description of the Related Art
In general, personal computers (PCs), portable transmitters, or other personal information processors process texts or graphics using various types of input devices such as key board, mouse, or digitizer. However, as an application field of the PCs spreads, it is often difficult to apply these input devices to the PCs as an interface input device. Unlike these input device, a touch screen has been known as an input device which is simpler than the keyboard and the mouse, has less erroneous operation, allows a user to easily operate, or allows a user to carry it and to input characters with a hand. The touch screen is the most advanced input device replacing the keyboard and the mouse. The touch screen is implemented by mounting a touch panel to a monitor. A user touches the touch screen on the monitor with a hand to perform a desired task, so that an intuitive task can be achieved under a Windows operating system.
Such a touch screen may be widely used in computer based training and simulation, office automation, and education and game application fields. Recently, the touch screen is mounted and used to a portable communication device such as a mobile communication phone. The touch screen has a touch panel, a controller, a device driver, and application software as a fundamental construction. In addition to this, detecting method, arrangement, and performance in accordance with the fundamental construction have been widely known.
A display device with the touch panel operates in a reflection mode or a shade mode. In a case where the display device operating in the reflection mode, in a dark environment free from external light, light created by a light source included in the display device is reflected from a finger touching the touch panel and then enters a photo-sensor. The photo-sensor senses the entered light to judge touch coordinates. In a case where the display device operating in the shade mode, in a bright environment of external light, a shade occurs in a finger part by the external light. As the shade is introduced in the photo-sensor, the photo-sensor senses light corresponding to the shade to judge touch coordinates.
In conclusion, the display device with the touch panel may sense a touched part brighter than a peripheral environment in dark illumination to recognize touch coordinates. Further, the display device with the touch panel may sense a touched part darker than a peripheral environment in bright illumination to recognize the touch coordinates.
Meanwhile, in a case of a gray zone where illumination of light created by a light source of a backlight unit included in a touch panel display device is similar to that of external light, illumination of touch coordinates touching the touch panel does not appear darker or brighter than a peripheral zone. Due to this, touch recognition capability is reduced in the gray zone where illumination of light created by a light source of a backlight unit included in a touch panel display device is similar to that of external light.